It’s easy to break Picasso’s oeuvre into neat periods, but there’s plenty of work that doesn’t fit into any particular category and, thus, don’t always make it into museum exhibitions on the prolific painter. For example, the series of “light paintings” Picasso made over the course of a few days in 1949.

That year, Picasso was visited by an Albanian photographer named Gjon Mili. The MIT-educated engineer was 45 and at the height of his career as a photographer, while Picasso was 67, in the midst of a reckoning with his age. Mili apparently showed Picasso some of his work depicting motion, using stroboscopes and long shutter speeds to capture the actions of a dancer or athlete over the course of a few seconds. The new technology piqued Picasso’s interest; Mili invited him to give it a try.

So Picasso did his thing, in various darkened rooms of his studio. He drew a centaur, the figure of a woman, an elephant, and various faces using a small pen light. “He was so fascinated by the result that he posed for five sessions,” wrote Life magazine, for whom Mili was freelancing at the time. “Mili took his photographs in a darkened room, using two cameras, one for side view, another for front view. By leaving the shutters open, he caught the light streaks swirling through space.” The resulting images were published in a 1949 issue of Life, recently resurfacing after the magazine published about the archived images.

The photos are a wonderful kind of hybrid: They are portraits of an aging Picasso, shirtless and concentrating with the effort of drawing an image he couldn’t see; they’re also original drawings by one of the most celebrated artists of the 20th century.